The present invention relates generally to paperboard and cardboard products and, more particularly, to corrugated cardboard and structures for forming voids that are constructed therefrom that are resistant to mold growth.
It is commonly known in the construction industry to create spaces or voids in or under various types of concrete formations. For example, concrete formations below grade such as the structural foundation of a building often require a space or void between the foundation and the ground to accommodate expansion of the soil, thereby preventing damage to the foundation. Thus, it is often desirable to create a void between the structural floor and/or grade beams of a foundation and the underlying soil to accommodate upheaval of the soil. It may also be desirable to create a void between the walls of a foundation and the surrounding soil to accommodate a similar expansion of the soil below grade. In addition, voids can also be utilized above grade between concrete floor slabs to reduce the amount of concrete required and to make the resulting slab lighter.
Another type of concrete formation that sometimes requires a void is a concrete pillar or column. It is often desirable to create a void in a pillar or column to allow room for internal plumbing, electrical conduits or the like within the column. By forming a void in the column, the items within the column are protected and the cost of making the column can be reduced because less concrete is required.
Typically, these voids are created by placing a biodegradable support structure made of corrugated cardboard in the desired location. These support structures are configured to support the building structural components until the poured concrete is capable of holding its own weight. As the concrete dries, and as the cardboard eventually deteriorates, a void is left in the concrete formation. Examples of such support structures (which are known in the industry as xe2x80x9cvoidsxe2x80x9d) are available from VoidForm International Ltd. of Canada.
In recent years, however, engineers have become concerned in that mold and bacteria have been discovered in home and building basements and foundations. More specifically, engineers are concerned that cardboard voids may be the cause of the mold and bacteria in that the mold grows on the void and bacteria feeds on the cardboard. A need thus exists for corrugated cardboard that does not grow mold or bacteria and void-forming structures constructed from the cardboard that are used with concrete during construction projects.
Accordingly, it is an object of the present invention to provide corrugated cardboard that resists growth of mold and spores.
It is another object of the present invention to provide structures for forming voids in concrete during construction processes where the voids resist growth of mold and spores.
It is still another object of the present invention to provide a process for producing mold-resistant corrugated cardboard and structures for forming voids.
The present invention is directed to corrugated cardboard that resists the growth of mold and a process for producing it. The cardboard is particularly useful in the construction of void-forming structures. The cardboard is constructed from single and double face liners containing starch, biocide, water and pulp. The biocides in the liners include 5-chloro-2-methyl-4-isothiazolin-3-one, hypochlorite and sodium hydroxide and sodium bromide. A fluted medium is sandwiched between the single face and double face liners. Adhesive secures the fluted medium to the single face and double face liners. The adhesive is constructed from starch and diluting water and has mixed therewith biocides that include 1,2-benzothiazol-3(2H)-one and poly[oxyethylene(dimethyliminio)ethylene dichloride]. A protective coating, such as wax or polyurethane, may be disposed on one of the liners.
In the production of the cardboard, the liner biocides are added to the water that is used to dilute the starch that is mixed with pulp to form the single and double face liners. Starch and diluting water are combined to form the adhesive which is then mixed with the adhesive biocides. A fluted medium is sandwiched between the single face liner and the double face liner and is secured to the liners with the adhesive. The protective coating is then added to one of the liners.
The following detailed description of embodiments of the invention, taken in conjunction with the accompanying drawings and claims, provide a more complete understanding of the nature and scope of the invention.